Hex Dominant Method creates a free hex-dominant mesh, meshing surfaces with quad elements, extruding them into volume for some distance and then filling the remaining space with unstructured element types.
Note: When you perform Explicit Analysis with LS-DYNA, Hex Dominant Method is not recommended as it creates unsupported pyramid elements in the core.
To access the Hex Dominant Method control,
On the Tree Outline, right-click Mesh and click Insert > Method.
Or
On the Tree Outline, click Mesh and click Method in the Mesh Context tab on the Ribbon.
Select Method as Hex Dominant Method in the Automatic Method Details view.
Hex Dominant Method Details view has the following options:
Scope
Scoping Method: Allows you to scope geometry bodies or named selection. The default value is Geometry Selection.
Geometry Selection: Allow you to scope the geometry bodies. When you select Geometry Selection, the Geometry allows you to select the geometry from the Geometry window.
Named Selection: Allow you to scope bodies grouped under a named selection.
Definition
Suppressed: Allows you to suppress the selected control. The default value is No. When Suppressed is set to Yes, Active displays the status of the selected control. Active is read-only.
Method: Allows you to select the method.
Element Order: Allows you to select the element order. The default value is Use Global Setting. For information about the Element Order option, refer Method Controls and Element Order Settings.
Free Face Mesh Type: Allows you to select the shape of the elements used to fill the body. The available options are Quad/Tri or All Quad. The default is Quad/Tri.
All Quad: Allows you to create the quadrilateral mesh.
Quad/Tri: Allows you to create the mesh with both quadrilateral and triangular elements.
Control Messages: Provides message when the Hex Dominant Method fails. You can click Control Messages to view the message.
Hex dominant meshing is more suitable for:
Meshing bodies with large amounts of interior volume where stress concentrations are highest close to the surface of the bodies.
Rigid body meshes where mesh quality is not important.
Meshing bodies that require hex elements at the surface and where Sweep and MultiZone methods have failed to produce a mesh and when you lack time or the relevant skills to split the geometry to create successful mesh with Sweep or MutliZone methods.
Hex dominant meshing is less suitable for:
Models where high quality hex mesh is required. For such cases, the recommendation is to use MultiZone or Sweep methods to achieve high quality results.
Models where fast transition of the mesh can result in poor solution accuracy (such as CFD models). The Hex dominant approach can have very fast transitions at the core of the volume.
Models where pyramid elements are invalid as the Hex Dominant Method produces a lot of pyramids in the core. For example, Explicit physics calculations.
Note:
Mesh Matching for cyclic symmetry is not supported for hex dominant meshing.
Workbench assists you in determining if hex dominant meshing is applicable to your situation. When you apply the Hex Dominant option on a body or group of bodies, Workbench calculates the normalized volume to surface area ratio. If it detects a ratio less than 2, Control Message appears in a highlighted row under Definition in the Details View. If you click Yes, Click To Display, a warning message states that a low percentage of hex elements or poorly shaped hex elements may result. Suggestions are included for alternative meshing schemes.
The normalized volume to surface area ratio is defined by the following expression:
(Volume of body/(Surface area of body)3/2)/factor
where factor, the ratio for a unit sphere = (4/3 π)/(4 π)3/2
Adaptive refinement starting from a hex dominant mesh will result in remeshing of the structure with tetrahedrons.
Use Body or Face Sizing to obtain more uniform face meshing, which leads to more hexes by volume.
If you apply a local Sizing control to a solid body with a Method control set to Hex Dominant or Sweep, or to a sheet body with a Method control set to Quadrilateral Dominant, a near uniform quadrilateral mesh results on
all affected faces on a body meshed with Hex Dominant
the source face meshed with Sweep
all affected faces meshed with Quadrilateral Dominant
To obtain even more of a uniform quadrilateral mesh, set the Behavior of the Sizing control to Hard.
Meshing thin and complicated bodies (for example a cellular phone case), using Hex Dominant Method requires much smaller element sizes to give good quality hex elements. As a result, the number of elements may increase compared to using a tetrahedron mesh.